The invention relates to the generation and distribution of electric power generated by wind turbines. More particularly, the invention relates to adapting to rapid losses of electrical power loads on a wind turbine, such as the loss of an electrical power grid load.
Power transmission and distribution grids (“power grids”) transmit electrical energy from wind turbine generating facilities to electrical power customers. The power grid provides an electrical load for a wind turbine generator. The electrical load on the generator imposes a torque on the rotor of the generator. The rotor is turned by the wind turbine which in turn is rotated by the wind. The torque on the rotor from the grid load results in a torque applied to the wind turbine. The wind turbine is balanced based on the torque from the grid load. If the grid load is loss the wind turbine may become unbalanced.
Loss of the grid unloads the generator and typically results in a rapid loss of a torque load on the generator. This rapid loss of torque can lead to a dramatic and rapid acceleration of the wind turbine rotor. To avoid over speeding of the rotor a severe braking procedure has to be initiated, leading to high load forces and moments acting on the wind turbine structure, such as large bending moments being applied to the tower of a wind turbine.
Wind turbines are traditionally designed to withstand the forces resulting from a grid loss. For example, towers for wind turbines have thick walls and large connection bolts to, in part, withstand large bending moments resulting from an abrupt grid loss. The base for a wind turbine is traditionally designed to adsorb the forces applied to the tower by a loss of grid load. There is a long felt need for structures and methods that accommodate grid loss without applying large forces to the wind turbine.